sr. JOHN.] WIND RIVER RANGE—JURA-TRIAS, &C. 233 
some are apparently of recent date. Occasionally limited rock exposures 
are seen in the sides of the sinks, showing alternations of usually white 
to gray gypsum in layers from a few inches to 5 feet and more in thick- 
ness, and variegated reddish and drab clays and indurated layers. In 
the immediate neighborhood more or less extensive accumulations of 
calcareous spring deposits are met with, and at one point in the low bluff 
bordering the river intervale a copious stream issues from subterranean 
sources, its waters charged with mineral substances that render them 
unfit for use. One of the ancient spring orifices was examined, its di- 
mensions being about 50 yards one way by 30 in the other direction and 
10 to 15 feet deep, portions of the calcareous tufa walls remaining quite 
perfect, as also the exterior limits of the deposition from the overtlow. 
The sinks occur-even on the opposite side of the Green, where one ap- 
parently formed only a few days before was seen close beside the road, 
the terrace gravel-walls forming its sides retaining their vertical position 
at the time it was examined. Their origin may be attributed tv the 
solvent power of water acting upon the gypsiferous beds, and where the 
latter deposits lie near the surface their removal may cause the super- 
jacent earth to sink into the cavities thus formed. 
Overlying the Triassic beds in the southern portion of the ridge are 
found a series of imperfectly-exposed Jurassic rocks made up of varie- 
gated pink, drab, and light-drab clays, and dark and light limestones. 
At a locality near the south extremity of the ridge the latter beds yield 
a few characteristic Jurassic fossils, Camptonectes, &c., by which their age 
is definitely determined. The deposits incline about southeast at an 
angle of 16°, the exposures belonging to the east or southeast declivity 
of the before-mentioned broad, low anticlinal arch. <A short distance to 
the northeast gray sandstones and light-drab limestones, associated with 
variegated clays, appear in the slopes of a small stream draining the in- 
terval lying over against the mountain flank, where they show a dip of 
25° about east. Ascending east to the near vicinity of the mountain, 
a limited outcrop, consisting of a four-foot ledge of hard, pinkish gray 
and dirty buff, finely brecciated limestone, included in pale-red shales, 
was met with, dipping about east at an angle of 70°. The relation of 
the latter to the foregoing Jurassic strata was not satisfactorily deter- 
mined, but it may belong to a Post-Jurassic formation. 
In the adjacent mountain slope heavy-bedded buff magnesian lime- 
stone appears, associated with much silicious matter or passing into light- 
eray reddish-tinged sandstone and overlaid by typical Carboniferous 
limestones. At one place, near the southernmost exposures of the Pa- 
leozoic remnant, the heavy magnesian ledges, though the bedding is 
obscure, incline steeply to the eastward; but a short distance to the 
north the mountain flank exhibits the same overlying Carboniterous 
limestones dipping off the range to the westward. The steep easterly 
inclination of the Paleozoic strata at this locality may have some rela- 
tion to the Post-Jurassic exposures above alluded to, although it is pos- 
sible they belong to the west flank of the synclinal trough into which 
these beds were folded. To the south, 4 or 5 miles, in the neighborhood 
of Station XVI, Mr. Perry found a series of pale-reddish deposits similar 
in their lithological appearance to the Post-Jurassic above referred to, 
and which apparently impinge with easterly dip against the Archean 
wall that here forms the abrupt western flank of the range. The state 
of things observed in this quarter apparently indicates a fracture or 
fault extending parallel with and immediately along the foot of this part 
of the range, and which carried the Paleozoic series down a vertical dis- 
tance amounting to several thousand feet, subsequent erosion having 
